For example, Patent Document 1 discloses a stranded optical cable in the formation of an optical communication network. As shown in FIG. 5, the stranded optical cable 1 is configured such that plural loose optical cables 2a or tape optical cables 2b are bundled around a tension member 5, and that the entirety is covered with a common cable sheath 6. Each of the loose optical cables 2a or tape optical cables 2b is covered with a unit sheath 4, and it is made a multicore optical cable of 20 cores or so. The loose optical cable 2a is such that plural optical units 3a are loosely accommodated in the unit sheath 4, and each optical unit 3a is such that plural optical fibers 8 are bundled round a tension member 7 and are then covered with a sheath 9. The tape optical cable 2b is formed by stacking and then bundling plural tape fibers 3b in each of which several optical fibers are united in the shape of a tape.